Virus warning followed by all Safari tabs mysteriously closed.

I visited a seemingly legit website from a Google search on Safari. I immediately got a virus warning and backed out of the page. Seconds later, all my Safari windows were involuntarily closed, not by me. My Safari no longer had any open tabs and acted as though it had no history or recent use.

The timing makes these two events seem related. Can a hijacked website close tabs, take over and/or delete Safari info like this? Moreover, can a compromised site steal data from Safari memory?